Teach mkdef.pl to handle multiline declarations.
Teach mkdef.pl to handle multiline declarations.

For the moment, this is specially crafted for DECLARE_DEPRECATED because
that's where we found the problem, but it can easily be expanded to other
types of special delarations when needed.

Reviewed-by: Matt Caswell <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@openssl.org>

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl